The present invention relates to end closures for two-piece beer and beverage metal containers having a non-detachable operating panel. More specifically, the present invention relates to a method of reducing the volume of metal in an end closure.
Common easy open end closures for beer and beverage containers have a central panel that has a frangible panel (sometimes called a xe2x80x9ctear panel,xe2x80x9d xe2x80x9copening panel,xe2x80x9d or xe2x80x9cpour panelxe2x80x9d) defined by a score formed on the outer surface, the xe2x80x9cconsumer side,xe2x80x9d of the end closure. Popular xe2x80x9cecologyxe2x80x9d can ends are designed to provide a way of opening the end by fracturing the scored metal of the panel, while not allowing separation of any parts of the end. For example, the most common such beverage container end has a tear panel that is retained to the end by a non-scored hinge region joining the tear panel to the reminder of the end, with a rivet to attach a leverage tab provided for opening the tear panel. This type of container end, typically called a xe2x80x9cstay-on-tabxe2x80x9d (xe2x80x9cSOTxe2x80x9d) end has a tear panel that is defined by an incomplete circular-shaped score, with the non-scored segment serving as the retaining fragment of metal at the hinge-line of the displacement of the tear panel.
The container is typically a drawn and ironed metal can, usually constructed from a thin sheet of aluminum or steel. End closures for such containers are also typically constructed from a cut-edge of thin sheet of aluminum or steel, formed into a blank end, and manufactured into a finished end by a process often referred to as end conversion. These ends are formed in the process of first forming a cut-edge of thin metal, forming a blank end from the cut-edge, and converting the blank into an end closure which may be seamed onto a container. Although not presently a popular alternative, such containers and/or ends may be constructed of plastic material, with similar construction of non-detachable parts provided for openability.
One goal of the can end manufacturers is to provide a buckle resistant end. U.S. Pat. No. 3,525,455 (the ""455 patent) describes a method aimed at improving the buckle strength of a can end having a seaming curl, a chuckwall, and a countersink along the peripheral edge of a central panel. The method includes forming a fold along at least substantially the entire length of the chuck wall. The fold has a vertical length that is approximately the same length as the seaming curl, and a thickness that is approximately equal to the length of the remaining chuckwall wherein the fold is pressed against the interior sidewall of the container when the end is seamed to the container""s open end.
Another goal of the manufacturers of can ends is to reduce the amount of metal in the blank end which is provided to form the can end while at the same time maintaining the strength of the end. One method aimed at achieving this goal is described in U.S. Pat. No. 6,065,634 (the ""634 patent). The ""634 patent is directed to a can end member having a seaming curl, a chuckwall extending downwardly from the seaming curl to a countersink which is joined to a central panel of the can end. The method of the ""634 patent reduces the amount of metal by reducing the cut edge of the blank. This is accomplished by increasing the chuckwall angle from approximately 11-13 degrees to an angle of 43 degrees.
The method of the ""634 patent may decrease the diameter of the central panel. This could reduce area on the central panel that is needed for written instructions, such as opening instructions or recycling information. It may also restrict the size of the tear panel. Furthermore, because the angle of the chuckwall is increased, the space between the perimeter of the can end and the tear panel is increased. This could cause spillage during pouring and/or drinking.
The method of the ""634 patent also produces a countersink. The ""455 patent shares this aspect. The countersink is provided in the can end to improve strength. However, because the countersink is a narrow circumferential recess, dirt will often collect within the countersink. Additionally, the dirt is often difficult to rinse away due to the geometry of the countersink.
One object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis and has a substantially planar peripheral edge. The seaming curl defines an outer perimeter of the end member. The chuckwall extends downwardly from the seaming curl. The transition wall connects the chuckwall with the substantially planar peripheral edge of the central panel. The transition wall comprises a folded portion extending outwardly relative to the longitudinal axis.
Another object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis and has a substantially planar peripheral edge, a public side and a product side. The seaming curl defines an outer perimeter of the end member. The chuckwall extends downwardly from the seaming curl. The transition wall connects the chuckwall with the peripheral edge of the central panel and comprises a fold including a concave annular portion engaging the peripheral edge of the central panel.
Another object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis. The seaming curl defines an outer perimeter of the end member. The circumferential chuckwall extends downwardly from the seaming curl at an obtuse angle. The transition wall connects the chuckwall with the central panel, and the transition wall comprises a fold having a portion extending outwardly relative to the longitudinal axis and upwardly relative to the central panel wherein the fold has a thickness which is substantially less than a length of the chuckwall.
Another object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis and has a peripheral edge. The seaming curl defines an outer perimeter of the end member and is adapted for connecting the end member to a container body. The chuckwall extends downwardly from the seaming curl. The transition wall connects the chuckwall with the peripheral edge of the central panel, and comprises a fold extending outwardly relative to the longitudinal axis and upwardly relative to the central panel. The transition wall has a vertical length that is less than a length of the seaming curl.
Another object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis and has a peripheral edge, a public side and a product side. The seaming curl defines an outer perimeter of the end member. The chuckwall extends downwardly from the seaming curl. The transition wall connects the chuckwall with the peripheral edge of the central panel. The transition wall comprises a fold including a concave annular portion having an apex in engagement with the public side of the peripheral edge of the central panel.
Another object of the present invention is to provide an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The central panel is centered about a longitudinal axis and has a substantially planar peripheral edge, a public side and a product side. The seaming curl defines an outer perimeter of the end member. The chuckwall extends downwardly from the seaming curl. The transition wall connects the chuckwall with the peripheral edge of the central panel. The transition wall comprises a fold including a first leg extending downwardly from the chuckwall to a concave annular portion having a first apex in engagement with the public side of the peripheral edge of the central panel, a second leg extending upwardly from the convex annular portion to a convex annular portion, and a third leg extending downwardly from the convex annular portion to a radial bend portion joined to the peripheral edge of the central panel.
Another object of the present invention is to provide a method for forming an easy open can end member comprising a central panel, a seaming curl, a circumferential chuckwall, and a transition wall. The method includes the step of providing a can end shell including a central panel centered about a longitudinal axis having a peripheral edge, a public side and a product side, a seaming curl defining an outer perimeter of the can end shell, and a circumferential chuckwall extending downwardly from the seaming curl joined to a transition wall. The method also includes the step of reforming the transition wall to form a fold having a portion extending outwardly relative to the longitudinal axis.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following drawings.